For the state of the art in this technology, please refer to D. W. Lubber's article "Grundlagen und Bedeutung der lokalen Sauerstoffdruckmessung und des pO.sub.2 Histograms fur die Beurteilung der Sauerstoffversorgung der Organe und des Organismus" in A. M. Ehrly "Messung des Gewebesauerstoffdruckes bein Patienten", publishing house Gerhard Witzstock, 1981, pages 11-18. According to the article the prior art is the following:
Reliable statements on the oxygen supply of the tissue which are usuable for medical diagnoses can only be determined via the determination of the statistical distribution of local oxygen-pressures in the tissue. In order to do so, the local oxygen pressure (pO.sub.2) has to be determined for a large number of measuring locations (usually at least 100).
The statistical evaluation of these measured values results in a so-called pO.sub.2 -histogram which provides in a diagram a diagnostically usuable statement on the current oxygen supply conditions. There is an example on page 15 of the mentioned article.
According to the above-mentioned article, an apparatus of the kind mentioned at the beginning is well-known using--according to page 14, middle of right column--probe tip diameters of less than 1 .mu.m. According to page 16, third paragraph, however, work with such micro probes involves major problems.
The disadvantages of micro probes can be mostly attributed to the danger of breaking. For this reason, they can be only used in highly specialized scientific laboratories and not in the clinic routine.
Furthermore, on page 16, third paragraph, there are mentioned unbreakable thicker probes imbedded in metal cannulas. But the latter are said to register unreliable measured values, most likely due to a local impact on the blood circulation. Thus, these unbreakable probes cannot be used for the relevant purposes.